I don't consistently get both labels assigned to the selected items in the Finder, but I don't get a conflict palette either.
Ah, so – you have the action “Set Tags”, whereas I think you want “Add Tags”.
Set Tags destroys any previously assigned tags.
As for the lack of a conflict palette I'm guessing you duplicated one macro and changed its parameters.
I've seen this bollix up a macro or two over some years, but I've never been able to duplicate the problem at will.
I'm guessing the two macros think they're the same one – maybe the UUID isn't getting differentiated as it's supposed to.
Upon install I experienced the same problem as you – no C.P.
I was able to recreate the problem by duplicating your macros and changing the keyboard shortcut – so there's something reproducible using the given macro file.
To fix the issue I had to recreate the macros from scratch, although I was able to paste in the actions from the old macros.
In any case – I'm fairly sure this is a bug. @peternlewis – please take a look.